E5322. Effects of Aging on Iliac Bone Turnover Using 18F-Sodium Fluoride (NaF) PET/CT
  1. Shashi Singh; Stanford University
  2. Bimash Shrestha; KIST Medical College
  3. Miraziz Ismoilov; Florida Atlantic University
  4. William Raynor; Rutgers Robert Wood Johnson Medical School
  5. Thomas Werner; Hospital of the University of Pennsylvania
  6. Mona-Elisabeth Revheim; The Intervention Center, Rikshospitalet, Division for Technology
  7. Abass Alavi; Hospital of the University of Pennsylvania
PET/CT utilizing 18F-sodium fluoride (NaF) as a radiotracer can detect changes in bone metabolism earlier than structural imaging. Although the hip, lumbar spine, and forearm are major sites of bone loss with age, the ilium could also be affected. The use of NaF-PET/CT to study iliac bone turnover with aging is relatively unexplored. Hence, we investigated the effect of aging on iliac bone turnover using NaF-PET/CT in both men and women.

Materials and Methods:
NaF-PET/CT scans from 59 men and 44 women from the “Cardiovascular Molecular Calcification Assessed by 18F-NaF PET/CT” CAMONA study were analyzed. The mean ages were 47.3 and 47.9 years, respectively. An ROI delineating the ilium from the rest of the osseous pelvis was created by defining a medial and an inferior border. The medial border was defined as a line parallel to the sacroiliac joint, running 2 cm laterally along the joint contour. The inferior border was defined as a straight line traversing from the most inferior point of the sacroiliac joint to a point 2 cm above the superolateral aspect of the acetabulum. Joint disease in the sacroiliac joint and acetabulum may confound measurements of bone turnover; hence, they were intentionally excluded using these anatomical criteria. The ROI was obtained by applying a Hounsfield unit threshold to segment bone, followed by a morphological closing algorithm to include uptake within the medullary cavity (OsiriX MD version 12.5.2 software; Pixmeo SARL; Bernex, Switzerland). Global mean standardized uptake value (global SUVmean) was then calculated as an average of SUVs from voxels within this ROI. Correlation between variables was assessed using the Pearson correlation coefficient.

NaF uptake in the ilium was negatively correlated with age on both right (r = -0.27, p = 0.006) and left (r = -0.22, p = 0.02) sides. Moreover, there was stronger negative correlation with age in women on both right (r = -0.30, p = 0.04) and left (r = -0.31, p = 0.04) sides compared to the right (r = -0.26, p = 0.04) and left (r = -0.18, p = 0.18) sides in men.

NaF metabolism of iliac bone demonstrates decreased bone turnover in women compared to men with aging. Our results show that iliac NaF uptake decreases with age in both men and women, which supports the hypothesis that NaF-PET/CT may provide functional insights into bone metabolism and bone turnover in the ilium of asymptomatic individuals at an earlier stage than is possible with conventional structural imaging, suggesting that NaF-PET/CT imaging may improve our understanding of bone health status.